1. Field of the Invention
The present invention relates a method for press-forming a material to be worked to form a heat transfer member for a heat exchanger, on the one hand, and the heat transfer member manufactured by the above-mentioned method, on the other hand, and especially to a method for applying a press-forming step to the material to be worked utilizing a plurality of molds so as to form a plurality of press formed portions arranged in a prescribed pattern, on the one hand, and the heat transfer member having such press formed portions, on the other hand.
2. Description of the Related Art
The heat transfer member of the heat exchanger, which is generally formed of a metallic sheet, is press-formed into a prescribed shape and then welded as an occasion demands, thus providing a finished product, which is to be put into practice. With respect to manufacture of the heat transfer member with the use of the press-forming device, a set of metallic molds have conventionally been used. More specifically, the material to be worked is held between the molds. Motion of moving the molds closely to each other has formed a pattern of irregularities serving as the heat transfer face on the metallic thin sheet of the material to be worked. The heat transfer face has the opposite surfaces, which are to be come into contact with heat exchange fluids, respectively.
The heat transfer member has conventionally been formed in the manner as described above. Formation of the entirety of the heat transfer member is carried out with the use of a single set of molds, thus making it impossible to manufacture the heat transfer member having a larger size than that of the molds. Thus, the size of the molds restricts the size of the heat transfer member. Accordingly, restriction in size of the molds makes it hard to manufacture the heat transfer member having a large area, thus causing a problem.
An object of the present invention, which was made to solve the above-mentioned problems, is therefore to provide a method for manufacturing a heat transfer member, which permits to easily manufacture the heat transfer member having a larger size than molds of a press-forming device, by incorporating the molds into the press-forming device so as to be selectively applicable, and making an appropriate selection of the molds in view of the size of the material to be worked to carry out a press-forming step so that placement of a plurality of press-formed portions in a prescribed pattern copes with the whole shape of the heat transfer member to be manufactured, thus appropriately providing the elongated material to be worked with a pattern of irregularity, to perform an easy manufacture of the heat transfer member having the large size than those of the molds.
In order to attain the aforementioned object, a method of the first aspect of the present invention for manufacturing a heat transfer member comprises the step of:
subjecting a material to be worked, which is made of a metallic thin sheet, to a press forming utilizing a press-forming device to form a heat transfer member for a heat exchanger, said heat transfer member having a prescribed shape, said heat transfer member having on at least one portion thereof a heat transfer face that has opposite surfaces, which are to be come into contact with heat exchange fluids, respectively,
wherein:
said press-forming device comprises a pair of main molds for forming the heat transfer face on a prescribed portion of the material to be worked, which is to be conveyed in a single feeding direction, and two pairs of first auxiliary molds, which are disposed on upstream and downstream sides of the pair of main molds in the feeding direction of the material to be worked, so as to be exchangeable; and
a plurality of portions of the material to be worked is subjected to the press forming utilizing at least one pair of said pair of main molds and said two pairs of first auxiliary molds to form the heat transfer member having a plurality of press-formed portions in a prescribed pattern.
According to the features of the first aspect of the present invention, the press forming is applied to the material to be worked with the use of the pair of main molds and the two pairs of first auxiliary molds, which are disposed in the feeding direction of the material to be worked. The plurality of different press-formed portions is formed on the material to be worked in the prescribed pattern so as to perform formation of the heat transfer member. The press-formed portions are further formed on prescribed regions of the heat transfer member. It is therefore possible to appropriately form a prescribed pattern of irregularity or prescribed flat portions on the outer peripheral portion of the material to be worked, independently from the heat transfer face, thus providing desired functions. The thus manufactured heat transfer member can cope with different conditions of use. In addition, the press-forming steps can be applied together to the material to be worked, utilizing the plurality of molds, thus improving the efficiency of the press forming. Even when the material to be worked is elongated and long, the appropriate press-forming steps can be carried out to form the heat transfer faces and the other portions over the entire length. As a result, it is possible to form the heat transfer face having a larger size than that of the molds in a reliable manner, thus permitting increase in size per unit of the heat transfer member so as to manufacture the heat exchanger having the enhanced heat exchange effectiveness.
In the second aspect of the present invention, as an occasion demands, said press forming device may carry out at least one of operations of (i) applying simultaneously the press forming to the material to be worked within a prescribed area starting from one end thereof, with a use of said pair of main molds and one of said two pairs of first auxiliary molds, while keeping an other of said two pairs of first auxiliary molds in a non-contacting state with the material to be worked, and (ii) applying simultaneously the press forming to the material to be worked within a prescribed area starting from an other end thereof, with a use of said pair of main molds and said other of said two pairs of first auxiliary molds, while keeping said one of said two pairs of first auxiliary molds in a non-contacting state with the material to be worked.
According to the features of the second aspect of the present invention, the press-forming step can be applied simultaneously to the prescribed area starting from the one end of the material to be worked, with the use of combination of the pair of main molds and one of the two pairs of the first auxiliary molds or the combination of the pair of main molds and the other of the two pairs thereof, while keeping the remaining one of the two pairs of the first auxiliary molds in the non-contacting state with the material to be worked. The heat transfer face and the remaining press-formed portions can be formed simultaneously on the material to be worked, so as to be arranged in the prescribed pattern. It is therefore possible to form efficiently a plurality of the press-formed portions on the material to be worked at the minimum number of press-forming steps, thus remarkably improving the press-forming efficiency. When the press-forming step is carried out utilizing a certain pair of molds, the remaining pairs of molds are kept in the non-contacting state with the material to be worked, thus ensuring a desired shape of the heat transfer member.
In the third aspect of the present invention, as an occasion demands, there may be adopted a structure in which said press forming device further comprises two pairs of second auxiliary molds, which are disposed on opposite sides of said pair of main mold in a perpendicular direction to said feeding direction, so as to be exchangeable, each of said two pairs of second auxiliary molds being kept in any one of a state in which a press-forming operation utilizing the pair of second auxiliary molds is carried out in synchronization with a press-forming operation utilizing the pair of main molds and an other state in which the pair of second auxiliary molds is kept in a non-contacting state with the material to be worked; and the heat transfer member is formed so that a press-formed portion formed by means of the pair of second auxiliary molds and the heat transfer face are arranged in at least one area.
According to the features of the third aspect of the present invention, the press forming is applied to the material to be worked, utilizing the pair of main molds and the pairs of second auxiliary molds, which are disposed in the perpendicular direction to the feeding direction, as an occasion demands, so that the prescribed press-formed portion is formed side by side with the heat transfer face on the material to be worked, with the use of the pair of second auxiliary molds, thus providing the prescribed press-formed portions on the respective edges of the material to be worked. It is therefore possible to achieve an appropriate formation of the prescribed press-formed portions on the respective edges of the material to be worked, independently from the heat transfer face, so as to impart the prescribed functions to the respective portions of the heat transfer member, thus providing the heat transfer member coping appropriately with the various conditions of use. When the press-forming step utilizing the pair of second auxiliary molds is not required, the pair of them is kept in the non-contacting state with the material to be worked, thus ensuring a desired shape of the heat transfer member.
In order to attain the aforementioned object, a heat transfer member for a heat exchanger, of the fourth aspect of the present invention, is obtained by subjecting a material to be worked, which is made of a metallic thin sheet, to a press forming utilizing a press-forming device, said heat transfer member having a prescribed shape, and said heat transfer member having on at least one portion thereof a heat transfer face that has opposite surfaces, which are to be come into contact with heat exchange fluids, respectively,
wherein:
said heat transfer member is formed by inserting the material to be worked into the press-forming device, which includes a pair of main molds for forming the heat transfer face and a plurality pairs of auxiliary molds adjacent to a periphery of said pair of main molds, transferring the material to be worked in a single feeding direction, subjecting the material to be worked to a press forming utilizing the pair of main molds to form the heat transfer face at a central portion of the material to be worked and forming at least one flange portion having a prescribed shape on a periphery of the transfer face with a use of the plurality of pairs of auxiliary molds so that a plurality of press-formed portions are arranged in a prescribed pattern.
According to the features of the fourth aspect of the present invention, the material to be worked, which is made of a metallic thin sheet, is press-formed utilizing the pair of main molds and the pair s of auxiliary molds of the press-forming device so as to form the different press-formed portions in a prescribed pattern so that the respective portions of the material to be worked are formed into the heat transfer face and the flange portion. Especially, the peripheral portions of the heat transfer member have the suitable shapes serving as the flange portion, which provide the different functions from those of the heat transfer face, thus coping with the various conditions of use. Even when the material to be worked is elongated and long, the appropriate press-forming steps can be carried out to form the heat transfer faces and the flange portion over the entire length. As a result, it is possible to form the heat transfer face having a larger size than that of the molds in a reliable manner, thus permitting increase in size per unit of the heat transfer member so as to manufacture the heat exchanger having the enhanced heat exchange effectiveness.
In the fifth aspect of the present invention, as an occasion demands, there may be adopted a structure in which said flange portion comprises a plurality of flat portions having a prescribed width, which are formed continuously on a periphery of the heat transfer face; and at least one recess or projection is formed so as to extend from an outer edge over said flat portion to lead to the heat transfer face.
According to the features of the fifth aspect of the present invention, the heat transfer member is provided with the flat portions, which are disposed continuously in the peripheral direction of the heat transfer member so as to serve as the flange portion, and with the recess or projection. When the heat transfer member is placed on the other heat transfer member so that the inner surfaces of them face each other, the flat portions of the former come into contact with the flat portions of the latter to form an internal cavity, which is surrounded by the flange portions and the respective heat transfer faces. The recesses or projections of these heat transfer members form a passage, which communicates with the internal cavity. As a result, positional determination of the recesses or projections of the heat transfer members makes it possible to form the passage through which heat exchange fluid flows in the assembled heat exchanger unit. In addition, it is possible to provide various kinds of flow of the heat exchange fluid, such as a cross-flow type, in the entirety of the heat exchanger. In case where the heat transfer members, which have been press-formed, are finally welded together to form an assembled heat exchanger unit, the flat portions serve as the portion to be welded, thus facilitating the welding operation.
In the sixth aspect of the present invention, as an occasion demands, there may be adopted a structure in which the material to be worked is formed of the metallic thin sheet having a rectangular shape; and said flange portion is formed on each of at least a pair of opposite sides of the periphery of the heat transfer face, said flange portion on one of the pair of opposite sides being provided with grooved portions, which are formed continuously in a direction parallel to the opposite sides so as to provide a smooth wave-shape cross section, and said flange portion on an other of the pair of opposite sides being provided with projection portions, which are formed continuously in a direction parallel to the opposite sides so as to provide a smooth wave-shape cross section.
According to the features of the sixth aspect of the present invention, the opposing portions of the flange portion are provided at the prescribed position with the smooth wave-shaped cross section to form rows of irregularity, in which the recesses or projections continue in parallel with the opposing portions of the flange portion. Such a structure imparts a sufficient strength against the bending stress that is applied to the flange portion having the recesses or projections, thus enhancing the strength of the flange portion. Accordingly, it is possible to surely keep the entirety of the heat transfer member in a proper shape. It is also possible to hold the flange portion of the heat transfer member to transfer it during manufacturing steps, preventing the heat transfer member from being deformed and insuring accuracy in shape. Formation of irregularity having the wave-shaped cross section improves formability of the flange portion, thus reducing rate of occurrence of defects in products.
In the seventh aspect of the present invention, as an occasion demands, there may be adopted a structure in which the material to be worked is formed of the metallic thin sheet having a rectangular shape; and each of at least a pair of opposite sides of said flange portion is provided with any one of at least one recess and at least one projection in at least one of a central position in an area, which is subjected to a single press-forming step utilizing said auxiliary molds, on one hand, and symmetrical positions with respect to said central position, on an other hand, said at least one recess and said at least one projection facing in a same direction.
According to the features of the seventh aspect of the present invention, the flange portion has any one of the at least one recess and the at least one projection in at least one of central position between an area of the material to be worked, which is subjected to the single press-forming step utilizing the auxiliary molds and symmetrical positions with respect to the central position. The above-mentioned any one of the at least one recess and the at least one projection formed on one of the pair of opposite sides of the periphery of the material to be worked faces in the same direction as the other of them formed on the other of the pair of opposite sides thereof. When the heat transfer member is placed on the other heat transfer member so that the inner surfaces of them face each other and the latter is positioned upside down, the recess or projections of the former face those of the latter and the remaining portions of the flange portion come into close contact with each other. When the assembled heat exchanger unit is placed on the other assembled heat exchanger unit, the recess or projection of the former heat exchanger unit comes into contact with that of the latter heat exchanger unit. Accordingly, the recess or projection serves as a spacer for providing a space between the two adjacent heat exchanger units, thus maintaining a constant distance between the heat transfer faces, providing a uniform heat exchanging property and increasing strength of the heat exchanger. In addition, the recesses or projections face each other to form at least one passage on the side of the flange portion. The heat transfer member can be held at its passage portion to transfer it, thus making it possible to hold the transfer member in a proper manner and providing a safe transporting operation of the heat transfer member.
In the eighth aspect of the present invention, as an occasion demands, there may be adopted a structure in which the material to be worked is formed of the metallic thin sheet having a rectangular shape; and each of at least a pair of opposite sides of said flange portion is provided with any one of at least one recess and at least one projection in at least one of a central position in an area, which is subjected to a single press-forming step utilizing said auxiliary molds, on one hand, and symmetrical positions with respect to said central position, on an other hand, said at least one recess and said at least one projection facing in an opposite direction to each other.
According to the features of the eighth aspect of the present invention, the flange portion has any one of the at least one recess and the at least one projection in at least one of a central position in an area of the material to be worked, which is subjected to the single press-forming step utilizing the auxiliary molds and symmetrical positions with respect to the central position. The above-mentioned any one of the at least one recess and the at least one projection formed on one of the pair of opposite sides of the periphery of the heat transfer face faces in the opposite direction to the other of them formed on the other of the pair of opposite sides thereof. When the heat transfer member is placed on the other heat transfer member so that the inner surfaces of them face each other and the latter is positioned upside down, the projection of the former heat transfer member is received into the recess of the latter heat transfer member to prevent deviation of these members. In addition, the remaining portions of the flange portion come into close contact with each other so that the recess or projection serves as a guide member by which positional determination for placing the heat transfer members one upon another. It is therefore possible to make a rapid positional determination when the heat transfer members are placed one upon another during manufacture of the heat exchanger unit. The heat transfer member, which has been placed on the other heat transfer member, may not deviate from the latter during a transporting operation of them, thus enhancing working precision in the subsequent step.
In the ninth aspect of the present invention, as an occasion demands, there may be adopted a structure in which the material to be worked is formed of the metallic thin sheet having a rectangular shape; and said flange portion has any one of a shoulder portion having a prescribed width and an inclined portion, which extends from a peripheral edge by a prescribed length and is inclined from a remaining portion by a prescribed angle.
According to the features of the ninth aspect of the present invention, the flange portion formed in any one of the periphery of the material to be worked has any one of the shoulder portion having the prescribed width and the inclined portion, which extends from the peripheral edge by the prescribed length and is inclined from the remaining portion by the prescribed angle. When the heat transfer member is placed on the other heat transfer member so that the inner surfaces of them face each other and the shoulder portions or inclined portions face each other, a trough-shaped portion is formed on the flange portion. In addition, the remaining portions of the flange portion come into close contact with each other. It is therefore possible to direct the trough-shaped portion upward so as to serve as a receiving member for receiving the heat exchange fluid. As a result, there can be set appropriately a flow path for the heat exchange fluid in the heat exchanger unit into which the heat transfer members are assembled. Heat exchange conditions on the outer surface of the heat exchanger unit can be set in view of the use of the heat exchanger, thus coping with the various type of use.